The present invention relates to a semiconductor device having an identification number, and particularly to a technology for economically implementing a small-sized semiconductor device mountable to various objects.
An IC card for returning information in non-contact form by radio in response to an inquiry sent from an interrogator has actively been used in recent years. A small-sized semiconductor chip (IC) having a memory, a simple logic circuit, etc. has been built in the IC card. Each of semiconductor chips each having an identification number, which is similar to such a semiconductor chip as described above and is mountable to an object desired to perform identification in non-contact form, has been brought into sight. The semiconductor chips are respectively provided with read-only memories (ROM) in which identification numbers different every chips have been written.
A technology for implementing such a ROM has been disclosed in Japanese Patent Laid-open (Kokai) No. Hei 8-139208. According to the present method, identification numbers individually different from one another are written onto a semiconductor wafer every semiconductor chips by use of an electron-beam writing technology. Described specifically, the writing of the identification numbers is carried out by the cutting off of wiring patterns produced by electron-beam writing without having to use a glass mask.
According to the method, non-cut wiring patterns are temporarily formed by a photolithography process using the conventional glass mask as fixed patterns. Subsequently, a resist film is applied onto the semiconductor wafer and post-baked. Next, an electron beam is imaged or drawn onto a cut portion of the wiring pattern. Thereafter, a developer is used to remove the corresponding pattern at the electron-beam written portion. Further, a wiring at a predetermined portion of each wiring pattern is removed by etchant or dry-etching ions. Afterwards, the resist film is removed by an asher, followed by cleaning. Thus, it was necessary to pass a complex process for implementing patterning by the cutting of the originally intended wiring pattern.
As another method of providing ROM with identification numbers different every chips written therein, a technology for determining the presence or absence of contact holes according to an exposure process of a step-and-repeat system has been disclosed in Japanese Patent Laid-open (Kokai) No. Hei 10-55939.
According to the prior art, a method of economically implementing each semiconductor chip having an identification number cannot be provided. Namely, in order to write individually different identification numbers into semiconductor chips each having an identification number on a wafer as memories, electron-beam writing is mentioned as one method. At this time, however, the prior art cannot avoid the addition of a complex process and the execution of a complex proximity effect correction. Thus, it is not possible to achieve the efficient utilization of an expensive electron-beam writing device or writer. The method of economically implementing each semiconductor chip having the identification number cannot be offered. Incidentally, the proximity effect indicates that an electron beam is diffused into a resist to change an imaged or drawn shape. However, it is necessary to perform a process or correction having made allowance for its change.
As another method for forming each identification number, the exposure process of the step-and-repeat system is known. According to the present method, however, since the presence or absence of exposure is selected according to patterns while a mask is being moved bit by bit, the number of bits for the identification number increases and a huge processing time is required together with an increase in the number of chips fabricated on a wafer, thus degrading economical efficiency significantly. Incidentally, Japanese Patent Laid-open (Kokai) No. Hei 10-55939 has made reference to the fact that electron-beam writing can be adopted in place of the step-and-repeat system. However, since the electron-beam writing is used only for the formation of each identification number in a manner similar to the step-and-repeat system, a problem arises in a manner similar to the above-described electron-beam writing.
Next, in order to get the semiconductor device having the identification number into widespread use, it is necessary to implement the following items in addition to the solution of the above-described principal problems.
An item firstly taken as an illustration is to make it possible to efficiently place a semiconductor chip on a film-shaped thin mounting base substrate. For the purpose of its implementation, it is necessary to provide a method capable of avoiding the orthogonalization of a chip""s device surface to the mounting base substrate upon packaging or implementation, naturally keeping it horizontal to the mounting base substrate and economically realizing the packaging or implementation of a semiconductor device.
An item secondly taken as an illustration is to make it possible to handle a semiconductor chip having an identification number so as to coexist with a conventional barcode system. For the purpose of its implementation, it is necessary to provide a method which makes it possible to operate a barcode system with efficiency and economically apply a semiconductor device having an identification number.
An item thirdly taken as necessary is to make it possible to economically inspect a semiconductor device having an identification number without having to use a conventional expensive semiconductor tester when the semiconductor device having the identification number is inspected.
According to one aspect of the present invention, there is provided a method of manufacturing device wherein an identification number is configured by a 128-bit memory using a transistor, comprising a step for forming conductive regions which serve as components of the transistor, on the surface of a semiconductor substrate in plural form, a step for forming an insulating film over a plurality of the conductive regions, a step for selectively defining contact holes in the insulating film formed on the plurality of conductive regions by an electron-beam writing method to obtain the identification number, and a step for forming wirings connected to the conductive regions through the contact holes respectively.
According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device wherein an identification number is identified by a memory using a plurality of transistors, comprising a step for forming source and drain regions of a plurality of the transistors on the surface of a semiconductor substrate, a step for forming an insulating film so as to cover a plurality of the source and drain regions, a step for defining contact holes whose presence or absence are selected according to xe2x80x981xe2x80x99 and xe2x80x980xe2x80x99 stored in the memory, in the insulating film on the transistors by using an electron-beam writing method, a step for forming a wiring layer on the insulating film having the contact holes, and a step for thereafter forming a coil for the reception of a microwave on the semiconductor substrate.
According to a further aspect of the present invention, there is provided a semiconductor device wherein an identification number is configured by a 128-bit memory using a plurality of transistors, comprising source and drain regions of a plurality of the transistors, which are provided on the surface of a semiconductor substrate, an insulating film provided so as to cover a plurality of the source and drain regions, contact holes whose presence or absence are selected according to xe2x80x981xe2x80x99 and xe2x80x980xe2x80x99 stored in the memory, the contact holes being defined in the insulating film on the transistors, a wiring layer provided on the insulating film having the contact holes defined therein, and a microwave receiving coil formed on the semiconductor substrate with the wiring layer provided thereon.
According to a still further aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising a step for preparing a semiconductor substrate, a step for forming the semiconductor device inside a chip area which corresponds to the surface of the semiconductor substrate and whose plane long-side size is smaller than the thickness of the semiconductor substrate, a step for removing the semiconductor substrate from the back side until the thickness of the semiconductor substrate becomes thinner than the plane long-side size of the chip area, and a step for separating the semiconductor device in chip form.
According to a still further aspect of the present invention, there is provided an electronic device comprising a semiconductor device wherein an identification number is identified by a memory using a transistor, and a barcode, the semiconductor device including conductive regions which serve as components of the transistor, an insulating film formed so as to cover a plurality of the conductive regions, contact holes selectively defined in the insulating film on the plurality of conductive regions to obtain the identification number, wirings connected to the conductive regions through the contact holes, and a microwave receiving coil formed on a semiconductor substrate provided with a wiring layer, wherein the memory has an area for storing the same data as the barcode in addition to an area for storing the identification number.
According to a still further aspect of the present invention, there is provided a semiconductor device wherein an identification number is configured by a first memory through the use of a transistor, comprising conductive regions which serve as components of the transistor, an insulating film formed so as to cover a plurality of the conductive regions, contact holes selectively defined in the insulating film on the plurality of conductive regions to obtain the identification number, wirings connected to the conductive regions through the contact holes, a microwave receiving coil provided on the wirings, a resonance circuit including a capacitor and the microwave receiving coil, and a second memory for storing an encrypted code obtained by enciphering the identification number.